JP5658143B2 - Halogenated polysilane and plasma chemical treatment for producing the same - Google Patents

Description

  The present invention relates to a pure compound each having at least one direct Si-Si bond, the substituent of which consists of halogen or halogen and hydrogen, and in which the atomic ratio of silicon to substituent is at least 1: 1 Or a halogenated polysilane as a mixture of compounds.

This type of chlorinated polysilane is known as prior art (DE 10 2005 024 041 A1, DE 10 2006 034 061 A1, WO 2008/031427 A2, WO 81/03168, US 2005/0142046 A1, M. Schmeisser, P. Voss "Ueber das Siliciumchlorid [SiCl ₂ ] _x ", Z. anorg. Allg. Chem. (1964) 334, 50-56 (Schmeisser, 1964), US 2007/0078252 A1, DE 31 26 240 C2, UK 703,349). On the other hand, this type of chlorinated polysilane has a complete thermal reaction (Schmeisser) with chlorosilane heated in steam with or without reducing the action at relatively high temperatures (above 700 ° C). , 1964). The resulting chlorinated polysilane is faintly colored from dark yellow to yellowish light brown (Schmeisser, 1964, "Slightly greenish yellow, glassy, high polymer"). Spectroscopic studies have shown that polysilanes produced entirely thermally have a high proportion of short-chain, branched and cyclic molecules. Furthermore, the resulting mixture is heavily contaminated with AlCl ₃ due to manufacturing conditions (very high temperature).

  GB 702,349 discloses that when a silicon alloy reacts with chlorine gas at 190-250 ° C, a mixture of chlorinated polysilanes is condensed from the air stream. During distillation, the average molecular weight of the mixture is relatively low because only 2% of silanes have n greater than 6.

DE 31 26 240 C2 describes the production of wet chemical chlorinated polysilanes from Si ₂ Cl ₆ by catalytic reaction. Since the resulting mixture still contains catalyst, it is washed with an organic solvent to leave traces of solvent and catalyst. Moreover, the PCS obtained by this method is heavily branched. On the other hand, a wet chemical method is shown in US 2007/0078252 A1.
1. Reduction of halogenated allyl oligosilanes with sodium by splitting with HCl / AlCl ₃ aromatics.
2. Transition metal catalyzed dehydrogenation polymerization of allylated H-silane and subsequent deallylation with HCl / AlCl ₃ .
3. Anion-catalyzed ring-opening polymerization (ROP) of (SiCl ₂ ) ₅ with TBAF (Bu ₄ NF).
4). ROP of (SiAr ₂ ) ₅ with TBAF or Ph ₃ SiK followed by deallylation with HCl / AlCl ₃ .

  In all processes, the solvent / catalyst contaminated PCS is obtained once more.

H. Stueger, P. Lassacher, E. Hengge , bis in Zeitschrift fuer allgemeine und anorganische Chemie 621 ( 1995) pp. 1517~1522, Si ₅ Cl ₉ H is corresponding by boiling with Hg (tBu ₂₎ in heptane Changed to cyclopentasilane Si ₁₀ Cl ₁₈ . Alternatively, cyclization of naphthyllithium, K or Na / K with Si ₅ Ph ₉ Br in various solvents is followed by halogenation with HBr / AlBr ₃ .

It is also known to produce this type of halogenated polysilane by plasma chemical treatment. For example, DE 10 2005 024 041 A1 describes a method for producing silicon from halosilane, in which the halosilane is converted to a halogenated polysilane by the generation of a plasma discharge in the first step, and then the second step. Pyrolysis of silicon in 2 steps. In this known process, a high energy density is used for plasma generation (higher than 10 Wcm ⁻³ ) and the final product is not a very dense wax white to tan or brown solid. What is revealed by spectroscopic analysis is that the final product obtained has a relatively high degree of cross-linking. The high energy density used results in a high molecular weight product, resulting in insolubility and low fusibility.

Furthermore, a high-pressure plasma treatment for HSiCl ₃ synthesis is described in WO 81/03168, where PCS is obtained as a small by-product. Since these PCS are produced at very high gas temperatures, they are relatively short chains and are heavily branched. Moreover, this PCS is obtained under hydrogenated conditions (synthesis of HSiCl ₃ !) And has a considerable hydrogen content. US 2005/0142046 A1 describes the generation of PCS by electrostatic discharge to SiCl ₄ at standard pressure. Several such reactor using selective reaction of SiH ₄ to generate a Si ₂ H ₆ and Si ₃ H ₈ by connecting consecutively authors demonstrate that only short chain oligosilanes is formed The This situation is similar to DE 10 2006 034 061 A1, where a similar reaction is described, in which gaseous and liquid PCS are obtained with Si ₂ Cl ₆ as the main component (p. 3, [00161 ]). The authors describe a method that allows the molecular weight of PCS to be increased through the use of several reactors connected in series, but here only materials that change to a gas phase that is not decomposed can be obtained. . The authors also state this situation in the claims and describe the distillation for all PCS mixtures obtained in the claims.

Furthermore, in addition to chlorinated polysilanes, other halogenated polysilanes Si _x H _y (X = F, Br, I) are known in the prior art.

E. Hengge, G. Olbrich, Monatshefte fuer Chemie 101 (1970), pages 1068-1073, describes the production of sheet-structured polymer (SiF) _x . This sheet structure polymer (SiCl) _x or (SiBr) _x is obtained by reacting CaSi ₂ with ICl or IBr. After this, the halogen exchange is completed with SbF ₃ . However, partial decomposition of the layered structure of Si occurs. The resulting product contains an amount of CaCl ₂ stoichiometrically based on uncleaned CaSi.

The production of polyfluorosilane (SiF ₂ ) _x is described, for example, on pages 713-714 of M. Schmeisser, Angewandte Chemie 66 (1954). SiBr ₂ F ₂ reacts with magnesium at room temperature in ether to form yellow and highly polymerized (SiF ₂ ) _x . Compounds such as Si ₁₀ Cl ₂₂ , (SiBr) _x and Si ₁₀ Br ₁₆ can be interhalogenated using ZnF ₂ to yield the corresponding fluoride. Standard production methods for (SiF ₂ ) _x are shown, for example, on pages 2824-2828 of PL Timms, RA Kent, TC Ehlert, JL Margrave, Journal of the American Chemical Society 87 (1965). Here, (SiF ₂ ) _x leads SiF ₄ to silicon at 1150 ° C. and 0.13 to 0.26 hPa (hectopascal), and the resulting SiF ₂ with polymerization during subsequent thawing is −196 ° Manufactured by freezing in C. The colorless to pale yellow resin polymer melts when heated to 200-350 ° C. in vacuo, releasing all fluorine-substituted silanes from SiF ₄ to at least Si ₁₄ F ₃₀ . Silicon-rich polymer (SiF) _x remains, and (SiF) _x actively decomposes at 400 ± 10 ° C. to become SiF ₄ and Si. Lower perfluoropolysilanes are colorless liquids or crystalline solids that are more than 95% pure and can be separated by fractional condensation.

The influence of secondary or tertiary amines causes the polymerization of perfluorooligosilane.
FI 82232 B discloses a higher temperature reaction. SiF ₄ reacts with Si in an argon plasma flame to become SiF ₂ (0.8: 1 mol, containing 70% SiF ₂ ).

According to A. Besson, L. Fournier, Comptes rendus 151 (1911), pages 1055-1057, short-chain all bromine-substituted polysilanes are formed. Discharge into gaseous HSiBr ₃ produces SiBr ₄ , Si ₂ Br ₆ , Si ₃ Br ₈ and Si ₄ Br ₁₀ .

According to K. Hassler, E. Hengge, D. Kovar, Journal of molecular structure 66 (1980), pages 25-30, (SiPh ₂ ) ₄ and HBr are reacted in the presence of AlBr ₃ catalyst to produce cyclo-Si. ₄ Br ₈ is generated.
In H. Stueger, P. Lassacher, E. Hengge, Zeitschrift fuer allgemeine und anorganische Chemie 621 (1995), pages 1517-1522, Si ₅ Br ₉ H changes by boiling with Hg (tBu ₂ ) in heptane. To the corresponding biscyclopentasilane Si ₁₀ Br ₁₈ . Alternatively, cyclization of naphthyllithium, K or Na / K with Si ₅ Ph ₉ Br in various solvents is followed by halogenation with HBr / AlBr ₃ .

According to M. Schmeisser, Angewandte Chemie 66 (1954), pp. 713-714, subbrominated polymeric silicon, on the one hand, reacts SiBr ₄ with magnesium in a yellow form of ether, on the other hand ( In addition to SiBr) _x , other oligosilanes such as Si ₂ Br ₆ and Si ₁₀ Br ₁₆ are also produced by the action of SiBr _{4 on} elemental Si at 1150 ° C.

DE 955414 B also discloses a reaction at high temperatures. When the vapor of SiBr ₄ or Br ₂ passes through the coarse particles of silicon at 1000 to 1200 ° C. in vacuum, mainly (SiBr ₂ ) _x is generated in addition to a little Si ₂ Br ₆ .

In US 2007/0078252 A1, the ring-opening polymerization of cyclo-Si ₅ Br ₁₀ and cyclo-Si ₅ I ₁₀ by the action of Bu ₄ NF in THF or DME is described in the claims.

For example, E. Hengge, D. Kovar, Angewandte Chemie 93 (1981), pages 698-701, or K. Hassler, U. Katzenbeisser, Journal of organometallic chemistry 480 (1994), pages 173-175, The production of iodine-substituted polysilanes is reported. Under the reaction of AlI ₃ , phenylcyclosilane (SiPh ₂ ) _n (n = 4 to 6) or Si ₃ Ph ₈ reaction with HI can result in all-iodine-substituted cyclosilane (SiI ₂ ) _n (n = 4 to 6) or Si ₃ I ₈ is formed. Page 782 of M. Schmeisser, K. Friederich, Angewandte Chemie 76 (1964) describes various routes for producing total iodine substituted polysilanes. SiI ₄ vapor is directed onto elemental silicon at 800-900 ° C. under high vacuum to produce (SiI ₂ ) _{x in} a yield of about 1%. Thermal decomposition of SiI ₄ under the same conditions yields a product that is likewise very hydrolysable and soluble in benzene. Under high vacuum, due to the effect of glow discharge on the vapor of SiI ₄ , a yellowish reddish amorphous solid with a composition of (SiI _2.2 ) _x and insolubility in all common solvents. Iodide is obtained in 60-70% yield (based on SiI ₄ ). Thermal decomposition of this material in a high vacuum at 220-230 ° C. yields dark red (SiI ₂ ) _x and simultaneously forms SiI ₄ and Si ₂ I ₆ . The chemical properties of the resulting (SiI ₂ ) _x compound are consistent except for the solubility in benzene. When pyrolysis of (SiI ₂ ) _x is performed at 350 ° C in a high vacuum, a brittle solid of SiI ₄ , Si ₂ I ₆ and orange red is formed, and this solid has a composition of (SiI) _x . Have. (SiI ₂ ) _x reacts with chlorine or bromine at −30 ° C. to + 25 ° C. to produce benzene-soluble subhalide silicon mixtures such as (SiClI) _x and (SiBrI) _x . At high temperatures, the Si-Si chain is cleaved with chlorine or bromine and at the same time total iodine substitution occurs. A compound of Si _n X _{2n + 2} type (n = 2 to 6 for X = Cl, n = 2 to 5 for X = Br) is obtained. (SiI ₂ ) _x completely reacts with iodine in a cylinder tube at 90 to 120 ° C. to become SiI ₄ and Si ₂ I ₆ .

  The present invention is based on the task of creating a halogenated polysilane of the type described above which is particularly soluble and fusible. Furthermore, the manufacturing method of this halogenated polysilane is also provided.

According to the first embodiment, this problem is solved by the following because of the halogenated polysilane of the type described above.
a) the halogen is chlorine,
b) The hydrogen content of the polysilane is less than 2 atomic%,
C) The chain and the short chain branch of the ring contained in the polysilane are less than 2% by weight , the content of the branch part of the short chain part is less than 1% by weight based on the total production mixture,
d) having a Raman molecular vibrational spectrum of I ₁₀₀ / I ₁₃₂ > 1, where I ₁₀₀ represents the Raman intensity at ₁₀₀ cm ⁻¹ , I ₁₃₂ represents the Raman intensity at ₁₃₂ cm ⁻¹ , and
e) In the ²⁹ Si-NMR spectrum, the important product signal is in the chemical shift region from +15 ppm to -7 ppm.

In the second embodiment of the present invention, because of the above-mentioned type of halogenated polysilane, the defined problems are solved by the following.
a) halogen is bromine, and
b) In the ²⁹ Si-NMR spectrum, the important product signal is in the chemical shift region from -10 ppm to -42 ppm, -48 ppm to -52 ppm and / or -65 ppm to -96 ppm.

Preferably, the halogenated polysilane described ^{above, 110cm -1 ~ 130cm -1, 170cm} -1 ~ 230cm -1, with typical Raman intensities at 450 cm ^-1 ~ 550 cm ^-1 and 940cm ^-1 ~ 1000cm ^-1 ing.

  Preferably, the hydrogen content of the polysilane is less than 4 atomic percent.

In the third embodiment of the present invention, the above-described problems are solved by the following invention.
a) halogen is fluorine, and
b) In the ²⁹ Si-NMR spectrum, the important product signal is in the chemical shift region from 8 ppm to -30 ppm and / or -45 ppm to -115 ppm.

Preferably, the fluorinated polysilane has typical Raman intensities at about 180cm ^-1 ~ 225 cm ^-1, about 490 cm ^-1 ~ 550 cm ^-1 and about 900cm ^-1 ~ 980cm ^-1.

  Preferably, the hydrogen content of the polysilane is less than 4 atomic percent.

In the fourth embodiment of the present invention, the above-mentioned problems are solved by the following invention.
a) Halogen is iodine, and
b) In the ²⁹ Si-NMR spectrum, the important product signal is in the chemical shift region from -20 ppm to -55 ppm, -65 ppm to -105 ppm and / or -135 ppm to -181 ppm .

Preferably, the iodide polysilane has typical Raman intensities at approximately ^{95cm -1 ~ 120cm -1, 130cm -1} ~ 140cm -1, 320cm -1 ~ 390cm -1 and 480cm ^-1 ~ 520cm ^-1 ing.

  Preferably, the hydrogen content of the polysilane is less than 4 atomic percent.

  The invention also relates to halogenated polysilanes containing halogen substituents of several different halogens.

²⁹ Si-NMR spectra were recorded using a Bruker DPX 250 instrument with a pulse sequence zg30 at 250 MHz and referenced as external standard [δ ( ²⁹ Si) = 0.0] compared to tetramethylsilane (TMS) Is done. The acquisition parameters are TD = 32k, AQ = 1.562 s, D1 = 10 s, NS = 2400, O1P = -40, SW = 400.

  The Raman molecular vibration spectrum is determined as follows. What follows is that Dilor's XY 800 spectrometer with confocal Raman and emission microscopes, a liquid nitrogen cooled CCD, and laser excitation (T-sapphire laser implanted with an argon ion laser) can be adjusted. Detector, measurement at the same temperature as room temperature, excitation wavelengths in the visible region of the spectrum, especially wavelengths of 514.53 nm and 750 nm.

  The expression short chain as used herein relates to compounds of n = 2-6, where n is the number of Si atoms that are directly linked to each other. Therefore, polymers with n greater than 6 are considered long chains.

  "Nearly" means that the mixture contains less than 2%. “Mainly” means that the content of the relevant components in the mixture is greater than 50%.

  The “main chain” is composed of all silicon atoms in the compound linked by Si—Si bonds.

  Halogenated polysilanes formed according to the present invention are produced in a fairly “mild” (energy density) plasma state. As a result, the polysilane after production has a high average chain length (n = 9 to 25) and is easily soluble and fusible.

The degree of branching of the chlorinated polysilane is determined by the ²⁹ Si-NMR spectrum. It is known that the chlorinated polysilanes produced using the treatment according to the present invention have a low content of short-chain branching compounds and their branching sites represent a proportion of the total mixture of less than 1%. It has been. Branches appear in the ²⁹ Si-NMR spectrum δ = −20 to −40 ppm and δ = −65 to −90 ppm. In the standard ²⁹ Si-NMR spectrum of chlorinated polysilanes in the present invention, there is very little or no resonance in those ranges, which is clearly marked, for example, comparable to chlorinated polysilane products that produce heat. Characteristic, this chlorinated polysilane that generates heat has a high proportion of branch sites. This is related to the fact that the latter chlorinated polysilanes are thermodynamically more advantageous than chlorinated polysilanes with unbranched chains, and the latter are Therefore, thermal reactions are preferentially formed, while in plasma treatment, thermal reactions occur far from thermodynamic equilibrium, and branches that are more thermodynamically advantageous are of lower priority.

The content of cyclosilane is also determined by ²⁹ Si-NMR and Raman spectroscopy, and it is known that the content of small rings (Si ₄ , Si ₅ , Si ₆ ) is extremely low.

Furthermore, chlorinated polysilanes formed according to the present invention have a Raman molecular vibrational spectrum of I ₁₀₀ / I ₁₃₂ > 1. In particular, in the low frequency range, there is a strong Raman signal in the range of 95 to 110 cm ⁻¹ , while a much weaker Raman intensity is measured in the range of 120 to 135 cm ⁻¹ .

Purely thermally generated chlorinated polysilanes have a ratio of I ₁₀₀ / I ₁₃₂ of less than 1.

This can explain the following. Due to the cyclic chlorinated polysilanes, theoretically quantum mechanics calculations show strong eigenmodes especially between 120 cm ^-1 and 135 cm ^-1 . In contrast, calculations for linear halogenated polysilanes, for example, do not show any obvious mode in this range. In contrast, the strongest mode of the lowest frequency, linear compound is replaced by increasing the chain length to a smaller wavenumber. They appear as a Raman band between 95 and 110 cm ⁻¹ in the mixture of halogenated polysilanes. To that extent, the I ₁₀₀ / I ₁₃₂ criterion provides content information for cyclic or linear molecules.

The halogenated polysilanes produced in accordance with the present invention are further soluble in many solvents because they can be easily transferred from the reactor used for production. In particular, the halogenated polysilanes formed according to the present invention have good solubility in inert solvents such as SiCl ₄ , benzene, toluene, paraffin, etc., even at room temperature, cold solvents, warm or boiling solvents. This is a significant difference compared to halogenated polysilanes which are prepared according to the publication DE 10 2005 024 041 A1 and which are all insoluble or only slightly soluble in such solvents.

  Preferably, the halogenated polysilane according to the present invention is characterized by comprising only halogen or a substituent of halogen and hydrogen.

  Preferably, the halogenated polysilane formed in accordance with the present invention has predominantly long chains (average n = 8-20).

  Also, halogenated polysilanes formed in accordance with the present invention are different from established prior art polysilanes produced plasma-chemically, and untreated polysilane mixtures produced in this prior art have a small average chain length. Thus, the average chain length (average size of the main chain) of the untreated mixture resulting from the halogenated polysilane is preferably n = 8-20. Preferably, n of the short chain polysilane is 15-25 after distillation.

  Another distinguishing feature over the prior art is that the halogenated polysilanes according to the invention have a low hydrogen content (less than 2 atomic% or less than 4 atomic%) and in particular less than 1 atomic%. doing.

  Furthermore, since the polysilane according to the present invention is produced by plasma treatment, it is highly pure with respect to contamination with dopants / metals and solvents, and the salient feature of the polysilane according to the present invention is the method listed at the end. Thus, with respect to the wet chemical manufacturing method of polysilane, trace amounts of solvent and metal salt type reagents always remain in the product. In particular, the high-purity polysilane obtained by plasma treatment according to the present invention meets the requirements for use in photovoltaic cells, such as solar cells.

  Halogenated polysilanes are highly viscous to solid. For example, chlorinated polysilanes are greenish yellow to bright orange or reddish brown, for example brominated polysilanes are colorless to yellow.

Furthermore, the problem defined above is solved by the method for producing a halogenated polysilane described above as a halosilane reaction type with hydrogen using production by plasma discharge, and the halogenated polysilane has a mixing ratio of halosilane and hydrogen of 1 0 to 1: 2 and has an energy density of less than 10 Wcm ^{−3 for} plasma discharge.

The method according to the invention is characterized in that it uses plasma conditions that are "milder" than in the prior art and is associated with a plasma discharge that exhibits an energy density of less than 10 Wcm- ³ . Thus, while prior art plasma chemistry processes use energy densities greater than 10 Wcm ⁻³ , preferably the processes according to the present invention have an energy density of 0.2 to 2 Wcm ⁻³ .

  The energy density means the power input divided by the amount of excited gas at the moment of gas discharge.

  Furthermore, the treatment according to the invention is characterized by a low proportion of hydrogen in the starting mixture compared to the prior art. Thus, the mixing ratio of halosilane and hydrogen used in the present invention being 1: 0 to 1: 2 results in a further significant reduction in energy input corresponding to the halosilane to be decomposed. Preferably about 850-1530 kJ / mol halosilane.

  Preferably, the treatment according to the invention is carried out in the pressure range from 0.8 to 10 hPa. In general, this pressure range is higher than the prior art as low-pressure gas discharges (eg DE 10 2005 024 041 A1), and in the process according to the invention, the high pressure is a support means for plasma discharge (eg high-pressure gas discharge). It is clear that it can be achieved without discharge), while it is clear that it is necessary in the prior art (DE 10 2005 024 041 A1). Without the aforementioned support, the prior art can only work at pressures below 1 hPa.

  Also, the required low power coupling can achieve processing according to the present invention without support means. Thus, in the process of the present invention, ignition can occur without any problem at 100 W.

  On the other hand, as described above, the mixing ratio of halosilane and hydrogen used in the processing of the present invention is 1: 0 to 1: 2, and the mixing ratio in the prior art plasma chemical processing is 1: 2 to 1. : 20 (DE 10 2005 024 041 A1; WO 81/03168).

  Preferably, with regard to the reaction temperature at which the treatment of the present invention is carried out, in the reactor, the portion where the halogenated polysilane precipitates is at a temperature of -70 ° C to 300 ° C, especially -20 ° C to 280 ° C. Maintained. Generally, the reactor is kept at a relatively low temperature to prevent the generation of Si composition.

  Preferably, the treatment of the present invention can produce a mixed product having molecules with an average of 13-18 Si atoms.

  In the process of the invention, for example, a voltage or alternating electromagnetic field is used to produce a plasma discharge. It is preferable to emit high-frequency light at a relatively low pressure (several hPa).

In the process of the present invention, halosilane is used as a starting material. In the treatment of the present invention, halosilane is a compound of the H _n SiX _4-n type (X = F, Cl, Br, I, n = 0 to 3) and a mixture thereof. However, halosilanes mixed with halogen substitution can also be used in the treatment of the present invention.

  Moreover, the gas mixture (halosilane and hydrogen) used in the process of the present invention can be diluted with an inert gas and / or can include an admixture that promotes plasma generation. However, no inert gas admixture is required for the treatment of the present invention.

  In another embodiment of the process of the present invention, halosilane is added to the hydrogen stream and eventually passes through the plasma zone (remote plasma). In this case, both the halogen gas and the halosilane can be diluted with an inert gas and / or can include an admixture that promotes plasma generation. Halosilane is also used to dilute with halogen.

Preferably, in the process of the present invention, fluorinated silane or silane chloride is used as the halosilane. Particularly preferably, the starting compound is SiCl ₄ .

  In the production of the halogenated polysilane, the volume ratio of halosilane: hydrogen is 1: 0 to 1:20, more preferably 1: 0 to 1: 2.

1 is a ¹ H-NMR spectrum of Example 1. 2 is a ²⁹ Si-NMR spectrum of Example 1. 2 is a Raman molecular vibration spectrum of Example 1. 2 is a ¹ H-NMR spectrum of Example 2. 2 is a ²⁹ Si-NMR spectrum of Example 2. 2 is a ¹ H-NMR spectrum of Example 3. 3 is a ²⁹ Si-NMR spectrum of Example 3. 2 is a ¹ H-NMR spectrum of Example 4. It is a ²⁹ Si-NMR spectrum of Example 5. 4 is a Raman molecular vibration spectrum of Example 4. ^{1 is} a ¹ H-NMR spectrum of Example 5.

  The invention is described below on the basis of examples.

A mixture of 500 sccm H ₂ and 500 sccm SiCl ₄ (1: 1) is fed to the quartz glass reactor and the process pressure is kept constant in the range of 1.6-1.8 hPa. The change from the gas mixture to the plasma state is then effected by radio frequency discharge, and the chlorinated polysilane formed condenses on the quartz glass wall of the cooled reactor (20 ° C.). 400 W of power is input. After 2 hours, the yellow to orange-yellow product is removed from the reactor by dissolving in a small amount of SiCl ₄ . After removal of SiCl ₄ under vacuum, 91.1 g of polysilane is left behind in the form of an orange-yellow viscous mass.

The average molecular weight is determined by the freezing point depression method as approximately 1700 g / mol, and the average chain length of chlorinated polysilane (SiCl ₂ ) _n or Si _n Cl _{2n + 2} is approximately n = 17 for (SiCl ₂ ) _n , Si _n Cl _{In 2n + 2} , approximately n = 16.

In the mixed product, the ratio of Cl to Si, after decomposition by precipitation titration of chloride ions according to the Mohr method, is consistent with the Si: Cl = 1: 2 (empirical (analytical) chemical formula SiCl ₂ Is determined).

The hydrogen content is 0.0005% by weight and is therefore well below 1% by weight (similar to less than 1 atomic%) and can be read from the following ¹ H-NMR spectrum (FIG. 1). As shown, the total solvent δ = 7.15 ppm and the product δ = 4.66 ppm are compared. The content of solvent C ₆ D ₆ is approximately 25% by weight and the degree of deuteration is 99%.

Typical ²⁹ Si-NMR shifts at approximately 3.7 ppm, -0.4 ppm, -4.1 ppm and -6.5 ppm can be read from the following spectra (Figure 2). These signals are (1) and (2) typical of the SiCl ₃ final group (primary Si atom) signal, and (2) shifts typical of the SiCl ₂ group (secondary Si atom) signal. In the region, for example, as a linking ring in the linear chain region.

In addition, short-chain, low-content branched compounds such as decachloroisotetrasilane (especially δ = -32 ppm) and dodecachloroneopentasilane (especially δ = -80 ppm) have the following ²⁹ Si-NMR spectrum: (Figure 2). The integration of the ²⁹ Si NMR spectrum shows that the content of silicon atoms forming the branch sites in the short chain part is based on the total production mixture and is less than 0.6% by weight and thus less than 1% by weight.

Low molecular cyclosilanes are not detected in the mixture. ^{The 29} Si-NMR spectrum shows sharp signals at δ = 5.8 ppm (Si ₄ Cl ₈ ), δ = -1.7 ppm (Si ₅ Cl ₁₀ ), and δ = -2.5 ppm (Si ₆ Cl ₁₂ ). I can't find anything else.

A typical Raman molecular vibrational spectrum of a chlorinated polysilane is shown below (Figure 3). This spectrum has a ratio of I ₁₀₀ / I ₁₃₂ greater than 1, ie the Raman intensity at ₁₀₀ cm ⁻¹ (I ₁₀₀ ) is clearly higher than that at ₁₃₂ cm ⁻¹ (I ₁₃₂ ). The spectra of the thermally generated perchloropolysilane mixture and the calculated spectrum of octachlorocyclotetrasilane (Si ₄ Cl ₈ ) are given for comparison, in which case the ratio I ₁₀₀ / I ₁₃₂ is opposite Less than 1.

  In addition, this figure shows a theoretical curve portion as an example. Here, quantum chemical calculation method [Hohenberg P, Kohn W, 1964. Phys. Rev. B 136: 864-71; Kohn W, Sham LJ. 1965. Phys. Rev. A 140: 1133-38, W Koch and MC Holthausen, Density Functional Theory for Chemists, Wiley, Weinheim, 2nd Edition, 2000] is adapted to the multiple Lorentz peak function, which simulates an outline of experimental spectral analysis . In terms of absolute intensity, theoretical curves have been standardized to fit well with the diagram shown. The theoretical peak relative intensity can be obtained directly from first-principles calculations. Thus, a certain strength is shown to be typical for cyclic polysilanes. The Raman spectral point data indicate a low content of cyclic polysilane in the plasma-chemically produced polysilane mixture, which is consistent with the NMR data (see above).

A mixture of 300 sccm H ₂ and 600 sccm SiCl ₄ (1: 2) is fed to the reactor made of quartz glass, and the processing pressure is kept constant in the range of 1.5-1.6 hPa. The change from the gas mixture to the plasma state is then effected by radio frequency discharge, and the chlorinated polysilane formed condenses on the quartz glass wall of the cooled reactor (20 ° C.). 400 W of power is input. After 4 hours, the orange-yellow product is removed from the reactor by dissolving in a small amount of SiCl ₄ . After removal of SiCl ₄ under vacuum, 187.7 g of chlorinated polysilane is left behind in the form of an orange-yellow viscous mass.

The average molecular weight is determined by the freezing point depression method as approximately 1400 g / mol, and the average chain length of chlorinated polysilane (SiCl ₂ ) _n or Si _n Cl _{2n + 2} is approximately n = 14 for (SiCl ₂ ) _n , Si _n Cl _{In 2n + 2} , it is approximately equal to n = 13.

In the mixed product, the ratio of Cl to Si, after decomposition by precipitation titration of chloride ions according to the Mohr method, is consistent with the Si: Cl = 1: 1.8 (empirical (analytical) chemical formula SiCl _1.8. Is determined).

The hydrogen content is well below 1% by mass (0.0008% by mass) (similar to less than 1 atom%) and can be read from the following ¹ H-NMR spectrum (FIG. 4). As shown, the total solvent δ = 7.15 ppm and the product δ = 4.66 ppm are compared.

The content of solvent C ₆ D ₆ is approximately 27% by weight and the degree of deuteration is 99%.

Typical ²⁹ Si-NMR shifts at approximately 10.9 ppm, 3.3 ppm, -1.3 ppm and -4.8 ppm can be read from the following spectra (Figure 5). These signals are (1) and (2) typical of the SiCl ₃ final group (primary Si atom) signal, and (2) shifts typical of the SiCl ₂ group (secondary Si atom) signal. In the region, for example, as a linking ring in the linear chain region.

Also, short-chain, low-content branched compounds such as decachloroisotetrasilane (especially δ = -32 ppm), dodecachloroneopentasilane (especially δ = -80 ppm) (these signals are represented by Si-Cl group ( Region (3) that is typical for signals of (tertiary Si atoms) and shift region in (4) that is typical for signals of Si groups with only Si substituents (quaternary Si atoms) ) Can be read from the following spectrum (FIG. 5). ²⁹ Silicon that forms the branched site (Si group having only Si-Cl group (tertiary Si atom) and Si substituent (quaternary Si atom)) in the short chain part by integration of ²⁹ Si-NMR spectrum It can be seen that the atomic content is based on the total production mixture, 0.3% by weight and therefore less than 1% by weight.

Low molecular cyclosilanes are not detected in the mixture. ^{The 29} Si-NMR spectrum shows sharp signals at δ = 5.8 ppm (Si ₄ Cl ₈ ), δ = -1.7 ppm (Si ₅ Cl ₁₀ ), and δ = -2.5 ppm (Si ₆ Cl ₁₂ ). There are many signals in the region.

In SiCl ₄ solvent, a peak appeared at approximately -20 ppm.

A mixture of 200 sccm H ₂ and 600 sccm SiCl ₄ (1: 3) is fed to the quartz glass reactor and the processing pressure is kept constant in the range of 1.50 to 1.55 hPa. The change from the gas mixture to the plasma state is then effected by radio frequency discharge, and the chlorinated polysilane formed condenses on the quartz glass wall of the cooled reactor (20 ° C.). 400W of power is input. After 2 hours and 9 minutes, the orange-yellow product is removed from the reactor by dissolving in a small amount of SiCl ₄ . After removal of SiCl ₄ under vacuum, 86.5 g of chlorinated polysilane is left in the form of an orange-yellow viscous mass.

The average molecular weight is determined by the freezing point depression method as approximately 1300 g / mol, and the average chain length of chlorinated polysilane (SiCl ₂ ) _n or Si _n Cl _{2n + 2} is approximately n = 13 for (SiCl ₂ ) _n , Si _n Cl _{In 2n + 2} , it is approximately equal to n = 12.

In the mixed product, the ratio of Cl to Si is consistent with the empirical (analytical) chemical formula SiCl _1.7 after decomposition by precipitation titration of chloride ions according to the Mohr method. Is determined).

The hydrogen content is well below 1% by mass (0.0006% by mass) (similar to less than 1 atomic%) and can be read from the following ¹ H-NMR spectrum (FIG. 6). As shown, δ = 7.15 ppm of the total solvent and δ = 3.74 ppm of the product are compared. The content of solvent C ₆ D ₆ is approximately 30% by weight and the degree of deuteration is 99%.

Typical ²⁹ Si-NMR shifts at approximately 10.3 ppm, 3.3 ppm, −1.3 ppm and −4.8 ppm and short chain low content branched compounds such as decachloroisotetrasilane (especially δ = −32 ppm), Dodecachloroneopentasilane (especially δ = -80ppm) (These signals are typical for the Si-Cl group (tertiary Si atom) signal (3) and Si substituents (quaternary Si (In the shift region at (4)), which is typical for Si group signals with only atoms), can be read from the following spectrum (FIG. 7)

Also, short-chain, low-content branched compounds such as decachloroisotetrasilane (especially δ = -32 ppm), dodecachloroneopentasilane (especially δ = -80 ppm) (these signals are represented by Si-Cl group ( Region (3) that is typical for signals of (tertiary Si atoms) and shift region in (4) that is typical for signals of Si groups with only Si substituents (quaternary Si atoms) ) Can be read from the following spectrum (FIG. 7). ²⁹ Silicon that forms the branched site (Si group having only Si-Cl group (tertiary Si atom) and Si substituent (quaternary Si atom)) in the short chain part by integration of ²⁹ Si-NMR spectrum It can be seen that the atomic content is based on the total production mixture, 0.6% by weight, and therefore less than 1% by weight.

Low molecular cyclosilanes are not detected in the mixture. ^{The 29} Si-NMR spectrum shows sharp signals at δ = 5.8 ppm (Si ₄ Cl ₈ ), δ = -1.7 ppm (Si ₅ Cl ₁₀ ), and δ = -2.5 ppm (Si ₆ Cl ₁₂ ). There is no reliable resonance in the spectrum and there are many signals in the spectral region.

In SiCl ₄ solvent, a peak appeared at approximately -20 ppm.

A mixture of 300 sccm of H ₂ and 240 sccm of SiBr ₄ vapor is supplied to a quartz glass reactor, and the processing pressure is kept constant in the 0.8 hPa region. The change from the gas mixture to the plasma state is then effected by radio frequency discharge, and the brominated polysilane formed condenses on the quartz glass wall of the cooled reactor (20 ° C.). 140W of power is input. After 2 hours, the colorless product is removed from the reactor by dissolving in benzene. After removal of benzene under vacuum, 55.2 g of brominated polysilane remains in the form of a clear white mash.

The average molecular weight is determined by the freezing point depression method as approximately 1680 g / mol, and the average chain length of brominated polysilane (SiBr ₂ ) _n or Si _n Br _{2n + 2} is approximately n = 9 for (SiBr ₂ ) _n , Si _n Br _{In 2n + 2} , approximately n = 8.

In the mixed product, the ratio of Br to Si is consistent with Si: Br = 1: 2.3 (empirical (analytical) chemical formula SiCl _2.3 , after decomposition by bromide ion precipitation titration according to the Mohr method. ).

The hydrogen content is well below 1% by mass (0.01%) (similar to less than 1 atom%) and can be read from the following ¹ H-NMR spectrum (FIG. 8). As shown, the total solvent δ = 7.15 ppm and the product δ = 3.9 ppm are compared. The content of solvent C ₆ D ₆ is approximately 30% by weight and the degree of deuteration is 99%.

Typical ²⁹ Si-NMR shifts (FIG. 9) appear in the ranges of -15 ppm to -40 ppm, -49 ppm to -51 ppm, and -72 ppm to -91 ppm.

A peak appeared from the SiBr ₄ extract at approximately -90 ppm.

A typical Raman molecular vibrational spectrum of brominated polysilane is shown below (FIG. 10). This spectrum approximately ^{110cm -1 ~130cm -1, 170cm -1 ~230cm} -1, has a typical Raman intensities at 450cm ^-1 ~550cm ^-1 and 940cm ^-1 ~1000cm ^-1.

A mixture of 100 sccm H ₂ and 50 sccm SiF ₄ gas is supplied to the plasma reactor, and the processing pressure is kept constant in the 1.2 hPa region. The change from the gas mixture to the plasma state is then effected by radio frequency discharge, and the formed fluorinated polysilane condenses on the cooled (20 ° C.) reactor wall. 100W of power is input. After 2 hours, the colorless to yellowish beige to white product is removed from the reactor by dissolving in cyclohexane. After removal of the solvent under vacuum, 0.8 g of fluorinated polysilane remains in the form of a white to yellowish beige solid.

The average molecular weight is determined as approximately 2500 g / mol by the freezing point depression method, and the average chain length of fluorinated polysilane (SiF ₂ ) _n (M = 66.08) or Si _n F _{2n + 2} is approximately n = (SiF ₂ ) _n 38, Si _n F _{2n + 2} is approximately equal to n = 37.

The hydrogen content is well below 1% by mass (similar to less than 1 atomic%) and can be read from the following ¹ H-NMR spectrum (FIG. 11).

Typical ²⁹ Si-NMR shifts of fluorinated polysilanes appear in the range of -4 ppm to -25 ppm and / or -50 ppm to -80 ppm.

Raman molecular vibration spectra of fluorinated polysilane, approximately 183cm ^-1 ~221cm ^-1, has a typical Raman intensities at 497cm ^-1 ~542cm ^-1 and 900cm ^-1 ~920cm ^-1.

A mixture of 60 sccm of H ₂ and 60 sccm of SiI ₄ vapor is fed to a quartz glass reactor, and the processing pressure is kept constant in the 0.6 hPa region. Next, the change from the mixed gas to the plasma state is brought about by high frequency discharge, and the formed polyiodide is condensed on the quartz glass wall of the cooled reactor (20 ° C.). 100W of power is input. After 2 hours, the reddish yellow product is removed from the reactor by dissolving in cyclohexane. After removal of the cyclohexane under vacuum, 8 g of iodinated polysilane remain in the form of a reddish yellow to brownish solid.

The average molecular weight is determined by the freezing point depression method as approximately 2450 g / mol, and the average chain length of iodinated polysilane (SiI ₂ ) _n or Si _n I _{2n + 2} is approximately n = 9 for (SiI ₂ ) _n , Si _n I _{In 2n + 2} , approximately n = 8.

In the mixed product, the ratio of I to Si is determined to be Si: I = 1: 2.3 (in agreement with the empirical (analytical) chemical formula SiI _2.3 ).

  The hydrogen content is well below 1% by mass (similar to less than 1 atomic%).

Typical ²⁹ Si-NMR shifts of iodinated polysilanes appear in the range of -28 ppm to -52 ppm, -70 ppm to -95 ppm and / or -138 ppm to -170 ppm.

Typical Raman typical Raman molecular vibrational spectra, approximately ^{98cm -1 ~116cm -1, 132cm -1 ~138cm} -1, 325cm -1 ~350cm -1 and 490cm ^-1 ~510cm ^-1 iodide polysilane Has strength.

Claims (18)

As a pure compound or a mixture of compounds having at least one direct Si-Si bond, the substituents consisting of halogen or halogen and hydrogen, and wherein the atomic ratio of substituents to silicon is at least 1: 1 in the component In the halogenated polysilane of
a) the halogen is chlorine,
b) The hydrogen content of the polysilane is less than 2 atomic%,
c) The chain and the short chain branch of the ring contained in the polysilane are less than 2% by weight (however, the short chain indicates a compound in which the number n of Si atoms directly bonded to each other is 2 to 6) and short The branch site content of the chain portion is less than 1% by weight , based on the total product mixture;
d) having a Raman molecular vibrational spectrum of I ₁₀₀ / I ₁₃₂ greater than 1, where I ₁₀₀ indicates the Raman intensity at ₁₀₀ cm ⁻¹ , I ₁₃₂ indicates the Raman intensity at ₁₃₂ cm ⁻¹ ;
e) Halogenated polysilane characterized by its important product signal in the chemical shift region of +15 ppm to -7 ppm in the ²⁹ Si-NMR spectrum. As a pure compound or a mixture of compounds having at least one direct Si-Si bond, the substituents consisting of halogen or halogen and hydrogen, and wherein the atomic ratio of substituents to silicon is at least 1: 1 in the component In the halogenated polysilane of
a) halogen is bromine, and
b) Halogenation characterized by its important product signal in the chemical shift region of -10 ppm to -42 ppm, -48 ppm to -52 ppm and / or -65 ppm to -96 ppm in the ²⁹ Si-NMR spectrum. Polysilane. ^{110cm -1 ~130cm -1, 170cm -1 ~230cm} -1, claim, characterized by having a typical Raman intensities at 450cm ^-1 ~550cm ^-1 and 940cm ^-1 ~1000cm ^-1 2 The halogenated polysilane described in 1. As a pure compound or a mixture of compounds having at least one direct Si-Si bond, the substituents consisting of halogen or halogen and hydrogen, and wherein the atomic ratio of substituents to silicon is at least 1: 1 in the component In the halogenated polysilane of
a) halogen is fluorine, and
b) In the ²⁹ Si-NMR spectrum, the important product signal is in the chemical shift region from 8 ppm to -30 ppm and / or -45 ppm to -115 ppm,
The halogenated polysilane includes a long chain of n> 6. 180cm ^-1 ~225cm ^-1, halogenated polysilane according to claim 4, characterized in that it has a typical Raman intensities at about 490cm ^-1 ~550cm ^-1 and approximately 900cm ^-1 ~980cm ^-1 . As a pure compound or a mixture of compounds having at least one direct Si-Si bond, the substituents consisting of halogen or halogen and hydrogen, and wherein the atomic ratio of substituents to silicon is at least 1: 1 in the component In the halogenated polysilane of
a) Halogen is iodine, and
b) Halogens characterized in the ²⁹ Si-NMR spectrum whose important product signal is in the chemical shift region from -20 ppm to -55 ppm, -65 ppm to -105 ppm and / or -135 ppm to -181 ppm. Polysilane. Claims, characterized in that it has a typical Raman intensities at approximately ^{95cm -1 ~120cm -1, 130cm -1 ~140cm} -1, 320cm -1 ~390cm -1 and 480cm ^-1 ~520cm ^-1 6. A halogenated polysilane according to 6. 8. The halogenated polysilane according to claim 2, wherein the polysilane has a hydrogen content of less than 4 atomic% .   9. Halogenated polysilane according to any of claims 1 to 8, characterized in that it contains halogen substituents of several different halogens. 10. The halogenated polysilane according to any one of claims 1 to 9, characterized in that it contains more than 50% long linear chains .   11. The halogenated polysilane according to claim 1, wherein the average size of the main chain in the untreated mixture of halogenated polysilane is n = 8-20.   The halogenated polysilane according to any one of claims 1 to 11, wherein the average size of the main chain in the untreated mixture of halogenated polysilanes after distilling off the short-chain polysilanes is n = 15 to 25.   The halogenated polysilane according to any one of claims 1 to 12, wherein the halogenated polysilane is solid from high viscosity. In a process for producing a halogenated polysilane produced from a plasma discharge by reaction of halosilane with hydrogen, the mixing ratio of hydrogen to halosilane is 1: 0 to 1: 2, and 10 Wcm ^{−3 for} plasma discharge The method for producing a halogenated polysilane according to any one of claims 1 to 13 , wherein the method is carried out at a lower energy density. The method according to claim 14, wherein an energy density of 0.2 to 2 Wcm ⁻³ is used for the plasma discharge. 16. A method according to claim 14 or 15, characterized in that the energy input per halosilane equivalent used is 850-1530 kJ / mol halosilane. The method according to any of claims 14 to 16, characterized in that a pressure range of 0.8 to 10 hPa is used. The method according to any one of claims 14 to 17, wherein in the reactor, the portion where the halogenated polysilane precipitates is maintained at a temperature of -70 ° C to 300 ° C.

Images